Antioxidant composition



Patented Nov. 16, .1943

AN TIOXIDANT COMPOSITION Harry F. Lewis, Appleton, Wis., assignor, bymesne assignments, to The Pacific Lumber Company, San Francisco, Calif acorporation of Maine No Drawing. Application July 12, 1939,

Serial No. 283,993 I 9 Claims.

The present invention, a continuation-in-part of my co-pendingapplication, Serial No. 245,678, filed December 14, 1938, now Patent No.2,214,- 251, relates to antioxidant compositions and processes ofpreparing the same. More specifically the present invention relates toantioxidant compositions particularly adapted for use in stabilizinghydrocarbons of the type derived from petroleum. The claims of theco-pending application are directed to water soluble tannin and relatedphlobaphene extracts while the claims of the present continuingapplication are direct'ed-to distillates obtained bythe destructivedistillation of alcohol soluble tannin and phlobaphene extracts.

Many compositions including synthetic products and so-called naturalproducts have been suggested heretoforefor useas oxidation inhibitors. Arepresentative antioxidant frequently prepared by a synthetic processand considered to be one of the potent compositions on the market today,is a compound known as catechol, i. e. o-dihydroxy benzene. Arepresentative natural antioxidant of value for use in anti-knockasolines is a tar obtained in the destructive distillation of hard wood.While the antioxidants discovered by prior investigators have found wideuse, the art has long recognized the need for improved antioxidants ofrelatively low cost, together with commercially practical processes ofproducing the same.

Therefore, the principal object of the present invention is to provideimproved antioxidant compositions of relatively low cost.

' .Another object of the present invention is to provide an improvedprocess for preparing potent antioxidant compositions.

Other objects will be apparent as the description hereinafter proceeds.I have discovered that California redwood (i. e. the soft wood orconifer knownvas Sequoia sempervirens) is a potential source of newantioxidant compositions and intermediates thereof. I have alsodiscovered that the antioxidant, composition made up of tannins andrelated phlobaphenes (which possess unique antioxidant properties perse) as well as the antioxidant intermediates made up primarily of thewater insoluble phlobaphenes (which are relatively inactive per se) canbe readily extracted from redwood. I have further discovered thatimproved antioxidant compositions may be obtained from -the redwoodextract containing the tannin and the phlobaphene compositions, by thedestrucw tive distillation of the extract per se, i. e. in the above.

absence of the wood and non-extractives contained therein.

My investigations have shown redwood to be unique as a wood in that itcontains an unusually high percentage of the desired extractives, e. g.up to 32 percent, of peculiar redwood tannin and phlobaphenecompositions. Ordinarily, for extraction, I prefer to use an alcoholic(ethanol) solvent using redwood flour made from redwood waste, e. g.sawdust, chips, slash and particularly the stumps and roots whichcontain an unusually high percentage of the redwood tannin andphobaphene compositions. Any of the Well known extraction apparatus maybe used as the extracting means and'the products may be obtained in theusual manner by evaporation of the solvent. It will be understood thatthe suggested method outlined above is merely illustrative and that thepresent invention is not limited thereto. Any organic solvent thatdissolves both the redwood tannins and the redwood phlobaphenes such asthe esters including ethyl acetate, may be used in place of the ethylalcohol solvent mentioned In commercial practice, the solventisrecovered and re-used as the extraction medium.

The destructive distillation of the. wood-free tannin and phlobapheneextract is carried out in any type of distillation apparatus either atreduced pressures (e. g. 30mm. to 100 mm.) or at atmospheric pressure.Investigations have shown that products obtained at relatively lowpressures and consequently rather low distillation temperatures (e. g'.200 C.) are superior antioxidants. The yields of active antioxidant tarobtained at low temperatures are also considerably greater than theyields obtained at high temperatures, e. g. 375 to 400 C. Ordinarily,the temperature of the extract should be kept below 350 C., e. g.temperatures 'of 275-300 C.

The crude tar distillate collected on destructive distillation (whichincludes some solid material, together with tar oil) is soluble in etherand possesses an antioxidant value approximating catechol. The phenolicfraction of the tar i. e. the portion soluble in aqueous alkali (e. g.sodium hydroxide) solutions possesses a greater antioxidant value thaneither the ether soluble tar or catechol.

In carrying out comparative tests the following standard antioxidanttest using mineral oil was employed: A sample of '75 grams of oil wasbeing dispersed by means of a fritted glass gas distributor. Thebreakdown or chanse in the nature of the oil was followed by determiningthe development of acidity or rate of acid formation in a given sample.

Hydrocarbons first pass through an induction period during which no acidis formed. The

difference in the time required to produce acids depends primarily onthe type of oil being tested.

on the nature of impurities present and on the TABLE I 1. Mineral oilwith no added antioxidant Percentage Hours oi treatment acid formationTABLE II 2. Mineral oil with catechol antioxidant Percent Antioxidantgggg Hours 0.01....... -3 12.5

TABLE III 3. Mineral oil with ether soluble tar Percent antioxidant gggg I Hours 0.01 10-11 TABLE IV 4. Mineral oil with phenolic fraction oftar Percent antioxidant s gfgg Hours 0.01 18-19 In the table (1) showsthat in a blank run made with mineral oil and no added antioxidant. thatthe oil starts to break down after approximately 1'-1.5 hours treatment;(2) shows that in a run made with mineral oil and 0.01 percent cateohol,that the induction period is extended about 11 hours by the addition theinhibitor; (3) shows that in a run made with mineral oil and 0.01'percent (total) ether soluble'tar, that the induction period is.extended about 9 hours; and (4) shows that a run made with mineral oiland 0.01 percent (alkali soluble) phenolic tar that the induction periodisextended about 17 hours. The percentages oi antioxidant used in theabove table show that the crude tar approaches the relatively expensivecatechol in antioxidant value and that the phenolic tar fractionpossesses an antioxidant value of over 150 percent of the value obtainedby using catechol in above standard tests.

The "destructive distillation" composition of the present inventionshould not be confused w th the water soluble tannin and relatedphlobaphene "extract" described in my co-pending application. Thecomposition of the present invention, for example, is directed todistillates obtained by destructive distillation oiredwood extractscontaining both the water insoluble (alcohol soluble) redwoodphlobaphenes as well as the water soluble extract of my co-pendingaplication. The process or the present-invention makes it possible toconvert the relatively inactive water insoluble phlobaphenes into potentantioxidant compositions while at the same time retaining to asubstantial degree the desired anti oxidant properties ofredwood'tannln.

The process of the present invention and the antioxidant compositionsproduced thereby should not be confused with processes or productsobtained by the destructive distillation or wood. Investigations haveshown destructive distions,particularly the phenolic fraction.

tillation carried out in the usual manner in the presence of redwood perse to result in the loss of substantial amounts of antioxidationcomposi- The destructive distillation of the extract in accordance withthe present invention reduces phenolic loss and produces a phenolic tarhaving superior properties comparedto the phenolic tars obtained bydestructive distillation of the wood. Thus I the phenolic tars, forexample, obtained by the Y destructive distillation of wood (due .to thewood .fiber and other foreign materials contained therein) possessesrelatively lower antioxidant properties compared to the phenolic tarproduct obtained by the destructive distillation oi. the redwood extractin accordance with the present invention.

In addition to the above-the redwood extract has been found to lenditself readily to destructive distillation with the accumulation of theminimum of undesired residue. Wood on the other hand does not lenditself to a rapid and easy distillation and the enormous quantities orcharcoal by product produced by the destructive distillation of wood haslittle call in the o en market and its disposition presents a realproblem to those attempting to operate under the old process. 0!additional importance the present process has been found more economicaldue to lower overhead (e. g. heat, equipment, etc.) than'the previouslysuggested processes.

The novel process of the present invention, although directed primarilyto the preparation of antioxidant compositions, may be advantageouslyemployed in the production of phenols from redwood. The present process,for example, not only gives more phenols per weight of distillationmaterial but also gives more actual phenols caiculated back to wood. Thephenols (i. e. phenolic fraction) of the distillate may be extracted andseparated from the non-phenolic tar fraction by extraction with aqueousalkali hydroxide solutions. The free phenolics in turn may be 'obtained-by treating the alkali. metal phenolates with dilute acids, e. g.sulphuric acid.

The improved antioxidant compositions produced by the present inventionare relatively inexpensive and possess potent antioxidant. properties.-They may be used to'advantage with all types of petroleum hydrocarbons,but have been found of particular value as an anti-sludging agent foruse with the heavy mineral oils having I all modifications coming withinthe spirit andscope of the claims annexed hereto.

I claim:

1. The improved process of preparing an antioxidant tar distillatecontaining substantial amounts of phenolic materials which comprisesdestructively distilling a wood-free redwood tannin and phlobapheneextract at temperatures not exceeding 350 C. and a pressure notexceeding atmospheric pressure.

2. The improved process of preparing a tar distillate containing asubstantial amount of phenolic materials possessing potent antioxidantproperties which comprises destructively distilling a wood-freealcoholic redwood extract at temperatures of 200 to 300 C. and apressure below atmospheric pressure.

3. The process of producing a distillate containing phenolic materialswhich includes destructive distillation of a wood-free redwood ethanolextract consisting essentially of water insoluble phlobaphenes and watersoluble tannins and related phlobaphenes, said distillation beingcarried out in a partial vacuum at temperatures below 300 C.

4. The process of preparing an antioxidant tar distillate whichcomprises treating redwood flour with ethyl alcohol so as to extractredwood tannins and phlobaphenes contained in said flour, separating theextract thus obtained from the atures below 350 remaining insolublematerial, evaporating the ethyl alcohol from the extract, and thendestructively distilling the resulting wood-free extract in a partialvacuum and at temperatures below 5. The process of obtaining phenolicmaterials which comprises producing a redwood tar distillate inaccordance with the process of claim 5, then subjecting said tar to atreatment with an aqueous solution of sodium hydroxide so as to extractand separate the phenolic fraction of said tar from the non-phenolicresidue, and finally freeing the phenols by addition of dilute acid tothe alkaline extract.

6. Redwood tar possessing improved antioxidant properties consisting oftar distillates obtained by destructively distilling a wood-free redwoodtannin and phlobaphene extract at temper- C. and a pressure notexceeding atmospheric pressure.

7. As a new product, a redwood tar containing a substantial amount ofphenolic materials, consisting of tar distillates obtained bydestructive distilling a wood-free redwood alcoholic extract at atemperature range of 200 to 300 C. and a pressure below atmosphericpressure.

8. As an antioxidant, a redwood tar distillate obtained by destructivelydistilling in a partial vacuum and at a temperature not exceeding 350 C.a wood-free ethanol redwood extract containing water insolublephlobaphenes and water soluble tannins and related phlobaphenes.

9. As an antioxidant, redwood phenolics prepared by the process ofclaim.

HARRY F. LEWIS.

